Apparatus and method for translating a nondescript signal into a distinctive recordable signal



March 25, 1969 F. E. WELD 3,435,413

APPARATUS AND METHOD FOR TRANSLATING A NONDESCRIPT SIGNAL INTO ADISTINCTIVE RECORDABLE SIGNAL Filed June 7, 1965 Sheet of 2 ITRANSLATING I I cIRcuIT I 2 I -I.0GIcs /-26 RECORDER I I II I I I 29 IFIG. I I DECODERS /24 I I8 I I I I l I STATION 7 STATION POWER I6 SUPPLYSTATION SOURCE 3 I TATION -I I 26 I I 38 46 I I I TRIGGER I I I SWITCH II I r 32 I I I 'I TRIGGER I I swI'rcI-I I IC+ -I I [42 CODING L I 1 4 II TRIGGER MATRIX I I SWITCH Z I IC+ 36 I l F ii I I I TRIGGER L I SWITCHI J II .I II II I I: GUN/G GATED /48 I RECORDER I I STEPPING I cIRcuITSWITCH I I DRIVER I 50 I I INVENTOR.

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ATTOR NEYS March 25, 1969 F. E. WELD 3,435,413

APPARATUS AND METHOD FOR TRANSLATING A NONDESCRIPT SIGNAL INTO ADISTINCTIVE RECORDABLE SIGNAL Filed June 7, 1965 Sheet W is mm B m @m WEa v 1R tfiw E 3K w M 325; zEo2w F .7 Y YwJ B A a 35m wzinmfifiom m OwMTV +0 3 1 mm NJ m m 5% N: mmv j 3 mm +0 I J mm S 3 TII, 3 on +0 ATTORNEYS.

United States Patent 3,435,413 APPARATUS AND METHOD FOR TRANSLATING ANONDESCRIPT SIGNAL INTO A DISTINCTIVE RECORDABLE SIGNAL Foster E. Weld,Newton Highlands, Mass., assignors to E. W. Bliss Company, Canton, Ohio,a corporation of Delaware Filed June 7, 1965, Ser. No. 462,028 Int. Cl.Gllb 5/78; G081) /00 US. Cl. 340-147 12 Claims ABSTRACT OF THEDISCLOSURE Apparatus and method are as disclosed herein for use intranslating a nondescript signal representative that a predeterminedcondition has occurred at a local station into a descriptive pattern ofcoded recordable pulses. The apparatus includes means, such as a signalgenerator, for purposes of providing a steady state output signal. Apulse generator serves to provide a train of time spaced pulses. Acoding matrix serves to receive the output signal and provide acharacteristic pattern of signal pulses at a plurality of outputcircuits which are representative of a particular local station. Astepping mechanism responds to the generated pulses for purposes ofsequentially stepping one step at a time for each generated pulse andfrom one of the output circuits to the next. A gating circuit respondsto the signal pulses and the generated pulses for developing arecordable pulse only upon occurrence in time of a generated pulse inthe absence of a signal pulse. This gating circuit is adapted to beconnected to a recording mechanism for recording an indication for eachrecordable pulse.

This invention pertains to the art of recording and, more particularly,to apparatus and method for translating a nondescript signal into adistinctive recordable signal.

The invention is particularly applicable for use in conjunction withfire alarm and police call systems and will be described with referencethereto; although it will be appreciated that the invention has broaderapplications.

A typical fire alarm system takes the form of a series loop connectingvarious local fire alarm boxes or stations together in a currentcarrying series circuit with a central station. A fire alarm call may besent from each local station to the central station by merely actuatinga lever at the local station, which in turn actuates a device forinterrupting the current flow in a distinctive manner resulting in acoded signal. The coded signal takes the form of a train of currentpulses which are time spaced according to a code representative of thecalling local station. The coded signal is transmitted through theseries circuit to recording equipment at the central station forrecording a mark for each received pulse, with the resultant pattern ofrecorded marks corresponding to the coded signal and, hence,representative of the calling station.

Recently, a combined telephone-telegraphy fire or police alarm systemhas been developed for use by municipalities and takes the form asdisclosed in United States patent application, Ser. No. 403,316, filedOct. 12, 1964, now Patent No. 3,384,714, entitled CombinedTelephone-Telegraphy System, assigned to the same assignee as thepresent invention. That system utilizes the time proven reliability ofthe typical series connected fire alarm stations. But, in addition tofire or alarm reporting, the system provides voice communication betweenthe calling local station and the central station through the seriescircuit. The new system also deviates from the typical 3 ,435,413Patented Mar. 25, 1969 fire alarm system in that when a person lifts atelephone handset at one of the local stations, a complex coded tonefrequency alarm signal made up of two distinct frequencies will betransmitted through the series circuit to the central station. At thecentral station a plurality of frequency decoders serve to decode thecomplex coded frequency signals, and for each complex signal receivedtwo decoders, representative of two different frequencies, will eachprovide a steady state output potential. A plurality of AND circuits atthe central station are each associated with a particular local firealarm station, and each is connected to a different combination of twodecoders. When two decoders connected to a particular AND circuitdevelop output potentials, then that AND circuit will also develop asteady state output potential representative of its associated localfire alarm station which transmitted the alarm signal. A lightassociated with each AND circuit will glow when that AND circuitdevelops an output potential to alert an operator at the central stationas to which local fire alarm station transmitted an alarm signal. Theoperator may then communicate by voice communication with the personinitiating the alarm signal for details of the fire, etc.

Many municipalities that desire to convert their typical fire alarmsystem to a combined telephoned-telegraphy system, as described above,also desire that means be provided for permanently recording which firealarm station transmitted an alarm signal. In the interests of econ omy,many of these municipalities further desire that any existing recordingequipment owned by the municipality for use with a typical fire alarmsystem be used with the combined telephone-telegraphy system. The steadystate output potentials developed by each AND circuit of the new systemare nondistinguishable from each other, rendering them nondescript andnot easily utilized for actuating recorder equipment normally used witha typical fire alarm system. Accordingly, means are required fortranslating the nondescript output potential developed by each ANDcircuit into a descriptive recordable signal representative of thecalling local fire alarm station.

The present invention is directed toward apparatus and method forsatisfying the foregoing needs of fire alarm systems for translatingnondescriptive signals into descriptive recordable signals, taking thepreferred form of coded signal pulses which may be utilized foractuating recording equipment, including the type normally used with atypical fire alarm system.

In accordance with the present invention, the translating apparatusincludes: a circuit responsive to the occurrence of a nondescript signalfor developing a steady state output signal; a pulse generatorresponsive to the output signal for generating a train of spaced pulses;a coding matrix having an input circuit for receiving the output signaland a plurality of output circuits, and having circuits for providing acharacteristic pattern of signal pulses at its output circuitsrepresentative of a particular local station; a stepping switch deviceresponsive to the generated pulses for sequentially stepping one step ata time for each generated pulse from one of the coding matrix outputcircuits to the next; and, a gating circuit responsive to thecharacteristic signals and the generated pulses for developing arecording pulse only upon the occurrence of a generated pulse and theabsence of a characteristic signal pulse.

In accordance with another aspect of the present invention, a method isprovided for translating a nondescript signal representative that apredtermined condition occurred at one of a plurality of local stationsinto coded recordable pulses, comprising the steps of:

(1) Generating a train of time spaced pulses upon the occurrence of anondescript signal;

(2) Applying a signal upon the occurrence of the nondescript signal toan input circuit of a coding matrix having a plurality of outputcircuits;

(3) Providing a characteristic pattern of coded signal pulses at theplurality of coding matrix output circuits representative of the localstation;

(4) Cycling a stepping switch from one coding matrix output circuit tothe next, one step at a time for each generated pulse; and,

(5) Recording an indication on a recording medium only upon theoccurrence in time of a generated pulse and the absence of a signalpulse.

By practicing the method described above, a coded pattern of indicationswill be recorded during each cycle of operation of the stepping switchrepresentative of the local station at which the predetermined conditionoccurred.

A primary object of the invention is to provide apparatus and method fortranslating a nondescript signal into a distinctive recordable signal.

Another object of the present invention is to translate a nondescriptivesignal representative of a particular one of a plurality of localstations in a fire alarm system into a distinctive recordable signal inthe form of coded pulses which may be used by a municipalitys existingrecorder equipment for recording a coded pattern of indicationsrepresentative of the particular local station.

These and other objects and advantages of the invention will be comeapparent from the following description of the preferred embodiment ofthe invention as read in connection with the accompanying drawings inwhich:

FIGURE 1 is a system block diagram illustrating a plurality of seriesconnected calling stations and a central station;

FIGURE 2 is a block diagram of one embodiment of the present invention;and,

FIGURE 3 is a schematic diagram illustrating in greater detail thepreferred embodiment of the invention.

Referring now to the drawings and more particularly to FIGURE 1, thereis illustrated in block diagram form one application of the preferredembodiment of the invention as applied to a fire alarm system, which ispreferably constructed in accordance with United States application,Ser. No. 403,316, identified previously, generally including a pluralityof local fire alarm stations 1, 2, 3 through N, connected together inseries across a central station power supply source 10 through centralstation equipment 12. The power supply source 10 and central stationequipment 12 may be located, for example, at the fire departmentheadquarters and the various local stations 1 through N may be locatedat desired locations Within the fire alarm system. The several stations1 through N are connected together in series by means of a singlemetallic circuit 14 through which direct current flows, in accordancewith the arrow i illustrated in FIG- URE 1, having a constant value onthe order of 100 milliamperes supply by the power supply source 10.Power to operate each local station 1 through N is obtained from thedirect current flow in circuit 14. A pair of encoders are located ineach local station and serve, upon lifting of a handset at the station,to develop a pair of frequency signals which are combined andtransmitted through circuit 14 as a complex coded tone frequency signalrepresentative of the calling station to the central station 12. Acapacitor 16 is connected across the power supply source 10 to preventthe complex coded tone frequency signals from being coupled to the powersupply source. The central station equipment 12 includes couplingcircuitry 18, which serves to couple received tone frequency signalsfrom the calling local station to decoder circuitry 24 including aplurality of decoders for decoding the complex frequency signal. Foreach complex frequency signal received, two decoders, representative ofthe two combined frequency signals, each developing a steady stateoutput potential. The steady state output potentials of decodercircuitry 24 are applied to logic circuitry 26, which includes aplurality of logic AND circuits, each representative of one of the localstations 1 through N. Each AND circuit of logic circuitry 26 isconnected to a different combination of two decoders of decodercircuitry 24 and serves when both its decoders develop output potentialsto in turn develop a nondescript output potential representative thatits associated local station transmitted an alarm signal.

In accordance with the present invention, a translating circuit 28 isprovided for translating the nondescript output potentials developed bythe AND logic circuits of logic circuitry 26 into descriptive recordablesignals for application to a recorder 29. The translating circuit 28 isillustrated in greater detail in block diagram form in FIGURE 2, andgenerally includes: four trigger switches 38, 40, 42, and 44; a codingmatrix 46; a gated stepping switch driver 48; and, a gating circuit 52.Each trigger switch has an output circuit connected to one of aplurality of input circuits of both the coding matrix 46 and the gatedstepping switch driver 48. The coding matrix has a plurality of outputcircuits connected to the stepping switch 50. The grated stepping switchdriver 48 has two output circuits; one connected to stepping switch 50and the other connected to an input circuit of gating circuit 52.Stepping switch 50 also has an output circuit connected to an inputcircuit of gating circuit 52, which in turn has an output circuitconnected to recorder The AND circuits of logic circuitry 36 areillustrated in simplified form in FIGURE 2 by switches 30, 32, 34, and36, which serve when closed to respectively connect 21 C+ voltage supplysource to trigger switches 38, 40, 42, and 44 within translating circuit28. Switches 30 through 36 may also represent individual local stationsof any system in which it is desired to record an indication that aparticular station has placed a calling signal, or that a particularcondition exists at or is noted by a local station. The calling signalin this instance is merely the closure of a switch, i.e., switches 30through 36.

Referring now to FIGURE 3, the trigger switches 38 through 44, codingmatrix 46, gated stepping switch driver 48, stepping switch 50 andgating circuit 52, as well as the recorder 29 are shown in greaterdetail in schematic diagram form. Trigger switches 38 through 44preferably take the form as silicon controlled rectifiers, as shown inFIGURE 2, and will be referred to as such hereinafter. Switches 30, 32,34 and 36 serve to respectively connect a C+ voltage supply source withthe gates of silicon controlled rectifiers 38, 40, 42 and 44. The anodesof rectifiers 38, 40, 42 and 44 are connected together in common with a13+ voltage source through a normally closed restoring switch 62, whichmay be manually opened by merely applying force to a spring type contactarm 64 in the direction of the arrow indicated in FIGURE 3. The cathodesof rectifiers 38, 4t), 42 and 44 are connected together in common with aB voltage supply source through diodes 54, 56, 58 and 60, respectively.Resistors 55, 57, 59 and 61 are connected between the gate and cathodeof rectifiers 38, 40, 42 and 44, respectively, and each resistor servesin combination with a load resistor 68 within the gated stepping switchdriver 48 as a voltage divider to prevent excessive voltage between thegate and cathode of its associated rectifier.

The gated stepping switch driver 48 includes a pulse generator 72 takingthe form of a relaxation oscillator 73 and a bi-stable multivibrator 75,connected across load resistor 68. Relaxation oscillator 73 takes theform of a unijunction transistor 74 having a first base B1, a secondbase B2 and an emitter 76 connected with one end of resistor 68 throughresistors 78 and 80. A timing capacitor 82 is connected between theemitter 76 and a B- voltage supply source. Base B2 is connected to the13+ voltage supply source through a current limiting resistor 84 andbase B1 is connected to the B voltage supply source through an outputresistor 86.

Bi-stable multivibrator of pulse generator 72 is connected across theoutput resistor 86 of relaxation oscillator 73 and includes a pair ofsilicon controlled rectifiers 88 and 90 connected together in push-pullfashion, with their anodes being directly connected together through acapacitor 92. The gate of rectifier 88 is connected to the gate ofrectifier 90 through a pair of series connected capacitors 94 and 96.The anode of rectifier 88 is connected with the B+ voltage supply sourcethrough a current limiting resistor 98. The cathodes of the rectifiers88 and 90 are directly connected to the B- voltage supply source. Thegates of rectifiers 88 and 90 are connected to the B voltage supplysource through current limiting resistors 102 and 104, respectively. Theoutput of the relaxation oscillator 73 is coupled to the input of thebi-stable multivibrator 75 by means of a current limiting resistor 106connected between the junction of the series connected capacitors 94 and96 and the junction of base B1 of unijunction transistor 74 and outputresistor 86.

The anode of rectifier 90 is connected to the base 108 of a germaniumpower transistor 110 within gating circuit 52 through a pair of seriesconnected resistors 112, 114, also located within gating circuit 52. Theemitter 116 of transistor 110 is connected to the B-] voltage supplysource through a diode 118, poled as shown in FIG- URE 3. A resistor 120is connected between the B+ voltage supply source and base 108 oftransistor 110 and a diode 122 is connected between the B- voltagesupply source and the collector 124 of transistor 110. Diode 118 andresistor 120 together serve to prevent false turn-on of transistor 110.Diode 122 serves as a surge suppressor to limit the induced voltage inmarking magnet coil 126. The power transistor 110 serves as a relay forenergizing a recorder marking magnet coil 126 of recorder 29 connectedacross diode 122. The recorder marking magnet coil 126 serves, whenenergized, to actuate a suitable marking arm 128 to print a mark 130 ormake a perforation, if desired, in a suitable recording medium 132driven by a suitable motor 134 at constant speed in the directionindicated by the arrow in FIGURE 3.

Stepping switch 50 includes a stepping switch magnet coil 136 connectedbetween the anode of rectifier 90 and the B voltage supply source, andwhen energized by anode current of rectifier 90 serves to actuate aratchet motor 138. A diode 140, poled as illustrated in FIGURE 3, isconnected across magnet coil 136 of stepping switch 58 and serves as asurge suppressor to limit the induced voltage across coil 136. Ratchetmotor 138 includes a ratchet wheel 142 mounted on a rotatable shaft 144driven by a spring biased ratchet pawl 146 which is pivotally mounted toa support 148 and spring biased by a spring 150. Each time magnet coil136 is energized, pawl 146 is withdrawn from engagement with ratchetwheel 142 and each time the coil is de-energized the pawl 146 drives theratchet wheel 142 one step by spring power from spring 150 so that shaft144 rotates one step at a time about its axis in the direction of thearrow illustrated in FIG- URE 3. A contact wiper 152 having threeequally spaced contact wiper arms 154, 156 and 158 is mounted on shaft144. The contact wiper arms 154, 156 and 158 are electrically connectedto the junction of resistors 112 and 114 of gating circuit 52 through acommon output circuit 164.

Coding matrix 46 may be of any suitable type capable of performing theoperation to be described hereinafter, but preferably comprises a firstplurality of ten conductors 160, vertically arranged in FIGURE 3,overlying and in perpendicular relationship to conductors 162,horizontally arranged in FIGURE 3. Conductors 160 are each connectedwith one of the output contacts or terminals 2 through 11 of codingmatrix 46. One of the wiper arms 154, 156 and 158 is, at the beginningof a cycle of operation of the stepping switch 50, in electrical contactwith terminal 1 of the stepping switch. The horizontally arrangedconductors 162 at terminals 166, 168 and 169 respectively serve as inputcircuits for the cathodes of silicon controlled rectifiers 38, 40, 42and 44. Coding matrix 46 is prearranged by means of a plurality ofdiodes 163 to provide a characteristic pattern of signals at its outputterminals 2, 3, 4, 5, 6, 7, 8, 9, 10 and 11 in accordance with thepositioning of the various diodes. Thus, for example, it will be noted,with respect to the uppermost horizontal conductor 162, that a diodeconnects terminal 166 with output terminal 3 and another diode connectsterminal 166 with output terminal 7. In this manner, as contact Wiper152 is sequentially stepped from terminals 1 through 11 current flowsfrom input terminal 166 to the common output circuit 164 only when thecontact wiper engages output terminal 3 or output terminal 7. This isrepresentative of a code 2, 3, 4. Similarly, it will be appreciated withreference to the next lower horizontal conductor 162, a plurality ofdiodes connect terminal 168 with each of the output terminals 2, 5, 6,7, 8, 9, 10 and 11, but not with output terminals 3 and 4. This isrepresentative of code 1, 2. Similarly, it will be noted that the nextlower horizontal row of diodes provides a characteristic pattern ofsignals at output terminals 2 through 11, representative of code 4, 1,2. Thus, it will be appreciated that the coding matrix 46 provides adifferent characteristic pattern of signals at its output terminals foreach of the calling stations, represented in FIGURE 3 by switches 30,32, 34 and 36.

The shaft 144 of the stepping switch 50 is provided with a cam 170having three cam lobes 172 thereon ex tending radially outward withrespect to shaft 144 and spaced equi-distant with respect to each other.A cam follower 174 rides on cam 170 as shaft 144 rotatesand serves tooperate a double pole, double throw switch 176. Switch 176 is providedwith a pair of movable contacts 178 and 180, illustrated in FIGURE 3, intheir normal position with cam follower 174 located on cam lobe 172.Switch 176 also has a stationary contact 182 for engagement with movablecontact 178 and is electrically connected to the junction of resistor 84and the B+ voltage supply source. Switch 176 also has a stationarycontact 184 in electrical contact with movable contact connecting acapacitor 186 in series with the B- voltage supply source to the B+voltage supply source through resistor 68 and diode 188, poled asillustrated in FIGURE 3, for charging the capacitor 186. The switch 176has another stationary contact 190 connected to the junction ofresistors 78 and 80, and serves when electrically connected with movablecontact 180 to provide a discharge circuit for capacitor 186 throughresistor 78.

Operation The operation of the translating circuitry 28, illustrated inFIGURES 1, 2 and 3, commences with receipt at the central station 12 ofa coded complex frequency alarm signal made up of two different distinctfrequencies transmitted by one of the local calling stations 1 to N. Thecoded complex frequency signal is applied through coupling circuitry 18to decoder circuitry 24, where two decoders, representative of the twocombined frequencies, each develops a steady state output potential. Thetwo steady state potentials are applied to logic circuitry 26 whereinone AND logic circuit responds to the two potentials and in turndevelops a steady state potential representative of one of the callingstations, for example, station 1. For purposes of simplifying theexplanation of the invention, the AND logic circuit is illustrated inFIGURE 3 by switch 30, which when closed provides a positive nondescriptsteady state potential from the C+ voltage supply source, representativeof station 1. Thus, with switch 30 closed, a positive potential will beapplied to the gate of silicon controlled rectifier (trigger switch) 38from the C+ voltage supply source, thereby forward biasing the rectifierwhich then conducts current through its anode to cathode circuit fromthe 13+ voltage source, through normally closed restoring switch 62 tothe input terminal 166 of coding matrix 46. Capacitor 186 will have beenpreviously charged in accordance with the polarities, illustrated inFIGURE 3, by current flow from the B+ voltage supply source to thecapacitor through diode 188 and resistor 68 to the B voltage supplysource. It is to be understood that the 13+ voltage supply sourcerepresents the positive side of a direct voltage supply source and theB- voltage supply source represents the negative side of the samevoltage supply source. With rectifier 38 forward biased and conducting,current will also flow from the 13+ voltage supply source through theanode to cathode circuit of rectifier 38, diode 54, and through the loadresistor 68 to the B- voltage supply source. Accordingly, capacitor 82,which is connected in parallel with resistor 68 through resistors 78 and80, will charge according to the polarities indicated in FIGURE 3. Whenthe voltage across capacitor 82 rises to the peak point voltage,approximately one-half of the value of the B+ voltage supply source, oftransistor 74, its emitter 76 will become forward biased and capacitor82 will discharge through the emitter 76 to base B1 of transistor 74 andoutput resistor 86. A positive voltage pulse will appear across outputresistor 86. Thereafter, the capacitor 82 will again charge anddischarge through transistor 74 and resistor 86 at a rate according to aRC time constant determined by the values of capacitor 82 andresistor'80.

Each positive voltage pulse developed across resistor 86 will be appliedto the gates of rectifiers 88 and 90 through coupling capacitors 94 and96, respectively. The first voltage pulse will forward bias bothrectifiers 88 and 90, but rectifier 88 will not remain conductive sinceresistor 98 limits the anode current of rectifier 88 to a value lessthan the required holding current. Rectifier 90, however, will remainconductive because series connected resistors 112, 114 and 120 inparallel with the stepping switch magnet coil 136 provides anode currentfor rectifier 90 of a value greater than that of the required holdingcurrent.

When rectifier 90 is conducting, capacitor 92 will charge throughresistor 98 and the anode to cathode circuit of rectifier 90. When thenext pulse is received from out-put resistor 86, rectifier 88 will againbecome momentarily forward biased and conductive to thereby dischargecapacitor 92, producing a negative voltage pulse at the anode ofrectifier 90 causing rectifier 90' to become reversed biased. Thus,rectifier 90 will be conducting and then non-conducting, respectively,under control of alternating pulses developed by relaxation oscillator73, whereby pulse generator 72 will develop a train of equally timespaced voltage pulses as long as rectifier 38 is conducting.

Each time rectifier 90 is conducting, current will flow from the B+voltage supply source through stepping switch coil 136 to the B voltagesupply source through the anode to cathode circuit of rectifier 90. Thiswill energize coil 136 causing pawl 146 to be pivoted in a clockwisedirection, as viewed in FIGURE 3, against the resistance of spring 150.Upon de-energization of coil 136, when rectifier 90 becomes reversedbiased, pawl 146 will be resiliently biased by spring 150 to step theratchet wheel 142 one step by spring power. Thus, each time pulsegenerator 72 energizes coil 136 there will result, upon the subsequentde-energization of coil 136, a one step movement of contact wiper 152.In this manner, contact wiper 152 will sequentially step one step at atime from contact terminal 1 to contact terminal 12.

When wiper arm 154 of contact wiper 152 is stepped from contact terminal1, as shown in FIGURE 3, to contact terminal 2, cam follower 174 willride olf cam lobe 172 whereby the double pole, double throw switch 176will be displaced from the position as illustrated in FIGURE 3 so thatmovable contact 178 engages stationary contact 1'82 and movable contact180 engages stationary contact 190. The engagement of movable contact178 with stationary contact 182 short circuits restore switch 62preventing turn-off of rectifier 38 for the duration of a complete cycleof wiper arm 154 from terminal 2 through terminal 11. The engagement ofmovable contact 180 with stationary contact 190 serves to dischargecapacitor 186 through resistor 78.

Transistor 110 of gating circuit 52 serves as a relay for recordermarking magnet coil 126, and is forward biased by anode current ofrectifier 90. Each time rectifier is conducting, a sufficiently negativepotential will exist on base 108 of transistor with respect to thatexisting on emitter 116 thereby forward biasing transistor 110. Thus,current will flow from the 13+ voltage supply source, through diode 118,the emitter 116 to collector 124 of transistor 110, and thence throughmarking magnet winding 126 to the B voltage supply source, therebyenergizing winding 126. Energization of marking magnet winding 126causes marking magnet arm 128 to record a mark on the recording medium132.

The recorder 29 will record a predetermined code, such as 2, 3, 4, asillustrated by the marking 130 in FIGURE 3, by the use of the diodecoding matrix 46. A diode 163 is placed in circuit connection betweenterminal 166 and matrix output terminal 3 and another diode 163 isplaced between terminal 166 and matrix output terminal 7. When contactiwiper arm 154 engages contact terminal I 3, or terminal 7, the B+voltage supply source is connected to the base 108 of transistor 110through the diodes 163, the common output circuit 164, and resistor 114.Each such connection applies a positive voltage pulse of suflicientmagnitude to the base 108 of transistor 110 to reverse bias thetransistor, preventing energization of recorder marking magnet winding126. Thus, each such connection serves to cancel a time coincidentrecording pulse received from pulse generator 72, leaving a spacebetween adjacent marks 130. As wiper arm 154 is sequentially stepped onestep at a time from terminal 1 to terminal 12, a characteristic patternof marks 130, according to code 2, 3, 4, will be recorded on recordingmedium 132.

At the completion of the recording cycle, i.e., the completion ofsequential stepping of wiper arm 154 from terminal 1 through terminal12, cam follower 174 will ride up a cam lobe 172, whereby the doublepole, double throw switch 176 will return to the position as illustratedin FIGURE 3. Contact wiper arm 156 will then be positioned in contactwith terminal 1 and contact wiper arm 154 will then be positioned incontact with terminal 12. Even if switch 30 had been momentarily closed,the current would continue to flow from the B+ voltage supply sourcethrough the rectifier 38 to maintain energization of the pulse generator72. When the double pole, double throw switch 176 is returned to theposition as shown in FIGURE 3, current will flow to recharge capacitor186 in accordance with the polarity indicated in FIGURE 3. The chargingof capacitor 186 will act as a momentary short circuit across rectifier38, causing de-energization of rectifier 38 and consequentdeenergization of pulse generator 72. The diode 188 in the chargingcircuit of capacitor 186 serves to prevent false triggering of the pulsegenerator 72 by discharging capacitor 186 when rectifier 38 becomesdeenergized.

When capacitor 186 becomes fully charged, the translating circuit 28will be in condition to begin a new cycle of operation.

I claim:

1. Apparatus for translating a nondescript signal representative that apredetermined condition occurred at a local station into a descriptivepattern of coded record able pulses and including means responsive tothe occurrence of said nondescript signal for providing a steady stateoutput signal, means responsive to said output signal for generating atrain of time spaced pulses, a coding matrix having an input circuit forreceiving said output signal and a plurality of output circuits, saidcoding matrix including means for providing a characteristic pattern ofsignal pulses at its output circuits representative of a particularlocal station, stepping means responsive to said generated pulses tosequentially step one step for each generated pulse from one of saidoutput circuits to the next, and gating means responsive to said signalpulses and said generated pulses for developing a recordable pulse onlyupon occurrence in time of a generated pulse and the absence of a signalpulse, said gating means adapted to be connected to a recording meansfor recording an indication for each said recordable pulse.

2. Apparatus as set forth in claim 1 wherein said means for providing anoutput signal includes a silicon controlled rectifier having a gate, ananode and a cathode and adapted to connect via its anode-cathode circuita voltage supply source with the input circuit of said pulse generatingmeans for energization thereof upon conduction of said rectifier.

3. Apparatus as set forth in claim 2 including normally closed restoringswitch means in said anode-cathode circuit for disconnecting saidvoltage supply source from said anode-cathode circuit to cause turnolfof said rectifier resulting in de-energization of said pulse generatingmeans.

4. Apparatus as set forth in claim 3 including normally open switchingmeans in circuit parallel with said restoring switching means, saidnormally open switching means being closed for short circuiting and thusdisabling said restoring switching means during the period of sequentialstepping of said stepping means.

5. Apparatus as set forth in claim 4 including cam means which cyclessaid stepping means, and cam follower means operatively connected tosaid normally open switching means for closing said switching meansduring the period that said stepping means sequentially steps acrosssaid output circuits of said coding matrix.

:6. Apparatus as set forth in claim 2 including means for de-energizingsaid pulse generator means after a cycle of operation of said steppingmeans across said output circuits of said coding matrix.

7. Apparatus as set forth in claim 6 wherein said deenergizing meansincludes a capacitor, a capacitor discharge circuit, two positionswitching means having a norm-a1 first position in which said capacitoris connected across the anode-cathode circuit of said rectifier, and asecond position in which said capacitor is connected across saiddischarge circuit for discharging said capacitor, means for operatingsaid two position switching means in response to said generated pulseswhereby upon the first step of said stepping means said switching meansis in its second condition and upon completion of said stepping meansacross the output circuits of said coding means the switching means isreturned to its normal first position, whereby as said capacitor chargesit effectively short circuits the anode-cathode circuit of saidrectifier causing turnoff thereof and de-energization of said pulsegenerating means.

8. Apparatus is set forth in claim 7 including cam means which cycleswith said stepping means, and cam follower means operatively connectedwith said two position switching means for positioning said switchingmeans in said second position during the period that said stepping meanssequentially steps across said output circuits of said coding matrix.

9. A method of translating a nondescript signal representative that apredetermined condition occurred at a local station into codedrecordable pulses and recording said pulses, the method comprising thesteps of: generating a train of spaced pulses upon the occurrence ofsaid nondescript signal, applying a signal upon the occurrence of saidnondescript signal to an input circuit of a coding matrix having aplurality of output circuits, providing a characteristic pattern ofsignals representative of a particular local station at said outputcircuits, cycling a stepping switch sequentially from one said outputcircuit to the next, one step at a time, for each generated pulse,recording an indication on a recording medium only upon the occurrenceof a generated pulse and the absence of a characteristic signal, wherebyfor each cycle of operation of said stepping switch a characteristicindication pattern is recorded on said recording medium represent-ativeof the particular local station.

10. A method of translating a nondescript signal representative that apredetermined condition occurred at a local station into codedrecordable pulses and recording said pulses, the method comprising thesteps of: developing a steady state output signal upon the occurrence ofsaid nondescript signal, applying said output signal to a coding matrix,developing a characteristic pattern of signal pulses representative ofsaid local station at a plurality of output terminals of said codingmatrix, generating a train of spaced pulses upon the occurrence of saidnondescript signal, cyclically stepping a switch arm one step at a timefor each generated pulse sequentially from one output terminal to thenext, and actuating a recorder to record on a recording medium anindication only upon the occurrence of a generated pulse and the absenceof a characteristic signal, whereby for each cycle of sequentialstepping of said switch arm a characteristic pat tern of indications isrecorded representative of a particular local station.

11. In central station equipment means adapted for use in receivingcoded station identifying frequency signals from a plurality of localstations and including a like plurality of means each associated with alocal station for developing a steady state nondescript output signalwhen its associated local station transmits a coded frequency signal,the improvement comprising: means for generating a train of spacedpulses, a coding matrix having a separate input circuit associated witheach of said calling stations and a lurality of output circuits,stepping means responsive to said generated pulses for sequentiallystepping one step at a time for each generated pulse from one of saidoutput circuits to the next, said coding matrix having means forproviding a different characteristic pattern of signal pulses at itsoutput circuits for each said local station, means coupled to saidoutput circuits via said stepping means and responsive to said signalpulses and said generated pulses for developing a recording pulse onlyupon the occurrence of a generated pulse and the absence of a signalpulse, and recording means responsive to said recording pulses forrecording an indication for each recording pulse, whereby for each cycleof operation of said stepping means a characteristic pattern ofindications is recorded representative of which local stationtransmitted a coded frequency signal.

12. In a telegr-aphy system having a plurality of local stations and acentral station connected togther in a series circuit and adapted to beconnected across a power supply source for maintaining current flow insaid series circuit, each said local station including means fortransmitting a coded frequency signal to said central station via saidseries circuit, a plurality of means at said central station eachassociated with one of said stations for developing a steady statenondescript output signal when its assocated station transmits a codedfrequency signal, the improvement comprising: means responsive to saidoutput signal for generating a train of spaced pulses, coding meansresponsive to said output signal for providing at a plurality of outputcircuits a different characteristic pattern of coded signal pulses foreach said local station, stepping means responsive to said generatedpulses for sequentially stepping one step at a time for each generatedpulse from one of said output circuits to the next, gating circuit meanscoupled with said stepping means and responsive to said signal pulsesand said generated pulses for developing a recording pulse only upon theoccureuce 11 12 of a generated pulse and the absence of a signal pulse,References Cited and recording means responsive to said recording pulsesUNITED STATES PATENTS v for recording an indication for each saidrecording pulse, whereby for each cycle of operation of said stepping3,206,545 9/1965 Kennedy et a1 1794 3,327,060 6/1967 Hogan 179-5 means acharacteristic pattern of indications is recorded 5 representative ofwhich station transmitted a coded frequency Signal DONALD J. YUSKO,Primary Examiner.

